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Center for Nonlinear Studies |
The rate and spatial distribution of sub-ice-shelf melting must be resolved to simulate ice-sheet changes in a warming world. Representation of key processes in simple models allows identification of the most critical parameters, and provides guidance on full ocean/ice-shelf/ice-stream coupling in future comprehensive ice-flow models. I present results from several studies. First, a two-dimensional vertical overturning streamfunction model of the thermohaline circulation is coupled with a simplified model of an evolving ice shelf. Significant changes in the shelf morphology are observed, notably an increase in basal slope near the grounding line, accompanied by shifts in the pattern of basal melting and freezing. Next, an ice-stream/ice-shelf flowline model is applied to show that grounding-line migration depends on the distribution as well as the magnitude of melting beneath an ice shelf, with concentrated melting near the grounding line producing significantly greater retreat than evenly distributed melting. Finally, I describe current efforts towards combining these two models effectively to produce a coupled ocean/ice-shelf/ice-stream simulation.